Need Help!- Mold making for automobile panels

[Greazzer]

Hello Everyone,

I am new to the forum.

I want to make molds for automobile panels, EG hood, trunk lid, and other parts. I have never done this. I have some mechanical skills, somewhat impatient (which is the killer), and my budget for a mold, EG Hood, is about $500.00. I am assuming I can buy the material to make a Hood will be about $500.00 so total investment is around $1,000.00. Here are my questions:

1. What is the best method to make a hood mold ?

2. Time investment ?

3. Anyone out there ever do this ?

Thanks in advance.

[Delw]

you wanna make a hood mold for a vehicle? and your thinking the material is going to cost you $500 ???????????????????? add about 1-2 "Zeros" to it and a ton of zero's to machine it.

Maybe I missunderstood what type of mold you want.

[ger21]

If you have an existing hood, you can lay up a mold right on it with glass fabric and epoxy.

Impatience here would be a very bad thing, as you'd probably end up with the mold permanently attached to your hood.

I'd spend the $500 practicing first.

[Greazzer]

Thanks for the replies. After making sure that the steel hood is in great shape, EG no dings, scratches, et cet., it looks like either a number of coats of wax OR PVC sprayed on, a few coats of that. That should provide a good releasing agent.

A few products exist which pour on like a goo but harden up. However, I will have to re-inforce the hardened goo product with fiberglass or something. Also, not sure how to handle the sides because they "go-in" or indented and I am concerned that will cause my mold to stick to my hood. Also, the layering of fiberglass looks tricky.

To focus my questions and issues:

1. The sides of the hood are indented in. I really cannot describe it, but I think all or if not most hoods are designed this way. Will this cause a problem?

2. Building up the sides (all four). Because there is 4" gap or so on parts, what do folks use for this? Clay?

3. After the goo hardens, any subsitute for fiberglass?

As for costs, I think $500.00 is very decent estimate.

1. Hood - $0
2. PVC - $38
3. "Goo" products $69-$129
4. Model Clay $50
5. Fiberglass & resin $200 + depends on how much I use.

[slowlearner]

Dont waste your money, unless you will be satified with a 1/2 " gap between panels. Both the fibreglass mold and the fibreglass hood made in the mold will shrink during the curing.

[rocketflier]

Originally Posted by slowlearner Dont waste your money, unless you will be satified with a 1/2 " gap between panels. Both the fibreglass mold and the fibreglass hood made in the mold will shrink during the curing.

No. A glass or carbon fiber part molded from the original will be a copy of the original

I'll post the link to some sites when I get back to the computer. One is the learning center at fibreglast.
Learning Center

{edit}

Smoothon
http://www.smooth-on.com/gallery.php?galleryid=441
Video at the bottom of the page shows using their spray on vacuum bagging material, but more importantly, making a hood from their mold.

http://www.smooth-on.com/gallery.php?galleryid=448
Photo sequence of making a rear wing.

Freeman supply, you may need a free login to view these:
http://www.freemansupply.com/video/e.../epoxymold.htm
http://www.freemansupply.com/video/exclusive/vacbag.htm

[Greazzer]

I guess I am doing a poor job explaining myself. Sorry. I want to make a mold of a hood, for example. The fiberglass will reinforce the goo that hardens over the hood. Not sure how the fiberglass will "shrink". I plan on making the hood out of carbon fiber. Not sure how carbon fiber will shrink. Has anyone out there made a carbon fiber hood ?

[rocketflier]

Originally Posted by Greazzer I guess I am doing a poor job explaining myself. Sorry. I want to make a mold of a hood, for example. The fiberglass will reinforce the goo that hardens over the hood. Not sure how the fiberglass will "shrink". I plan on making the hood out of carbon fiber. Not sure how carbon fiber will shrink. Has anyone out there made a carbon fiber hood ?

Not a hood, nosecones and fins,.. note my username.

Go through the links I posted and ask questions when you can better describe "goo".

[Greazzer]

Hey RocketFlier,

THANKS ! I think I am on the right track now. Have you tried this stuff ? The "goo stuff", one type is called vinylester gelcoat.

I have zero experience doing this, but my first step is trying to figure out how to make the mold. The links you gave were great. Have you ever made a hood, et cet?

Thanks again, and any other info would be appreciated. Thanks.

[rocketflier]

Originally Posted by Greazzer Hey RocketFlier, THANKS ! I think I am on the right track now. Have you tried this stuff ? The "goo stuff", one type is called vinylester gelcoat. I have zero experience doing this, but my first step is trying to figure out how to make the mold. The links you gave were great. Have you ever made a hood, et cet? Thanks again, and any other info would be appreciated. Thanks.

Gelcoat is typically the very outer layer of a fiberglass part or mold. Think of it as the paint layer on a wood sided house. It breaks/crack very easily and is backed by reinforcing layers. When they make boat hulls, they spray the mold with a gelcoat, then use a chop strand gun to lay down chopped fiber & polyester resin in layers. When the mold is pulled away, the boat surface is finished.

The resin (goo) we use is epoxy, but also commonly available/used is polyester. I haven't looked into vinyl ester,.. this should help more with 'goo':
Epoxy Resin vs. vinylester - polyester resin

You would probably have the best luck searching car forums for hood construction.

more up my alley:
Making a Fiberglass Two Piece Nose Cone Mold

Rocket Team Vatsaas THE DARK ART OF COMPOSITES -- Part One (Materials)
Rocket Team Vatsaas THE DARK ART OF COMPOSITES -- Part Two (How To)

Almost 3/4 of the way down:
Nike-Asp

[Greazzer]

Hey RocketFlyer --

I spent a bunch of time looking for someone who made a hood (or any car panel) in their garage. So far, no luck. There is one guy making a trunk lid on YouTube, but he's not even past the sanding part of the original. Do you think the "indent" part of the hood which runs on the left and right side of the hood would make the mold stick to the original? I think a few coats of wax, and few coats of PVC sprayed on is the best I can do for not having it stick EXCEPT for a design flaw. I prefer not to lose a hood. Once I get the mold, I think I am confident enough to do carbon fiber resin infusion. Looking for a kick butt vacuum pump right now. Any leads or other info is GREATLY appreciated. Thanks, and your work looks great, perfectly smoothed finish. That is what I am shooting for. Thanks again.

[rocketflier]

To be clear, those are not my work(s).

Any negative edge of the part is a problem. You won't be able to remove the original let alone any parts. Easiest solution is to clay over the negative. Alternative is to create a multipart mold, much like the 2 part nosecone molds. Layout the top of the hood, let that mold cure. On top of the mold, lay out the side/edges of the hood, let those cure. Remove the edge mold, then remove the hood from the top mold.

Making a mold of my front bumper need help! - Fiberglass Forums

This one is offering advice my search on "forum make a composite hood" turned up quite frequently:
Making a fiberglass hood. - Honda Forum : Honda and Acura Car Forums

They point out some good issues including the metal/fiberglass cracking problems and don't forget liability,...

You do understand you're not making 1 part? You're making a bunch that will be tossed as you work out issues.